The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
In many internal combustion engines, conventional overhead valvetrain assemblies include a rocker arm having a first end which engages a hydraulic lash adjuster, a second, opposite end which engages a valve stem and a roller or other friction reducing device in the middle of the rocker arm which engages a cam on a camshaft. So configured, there is no fixed axis about which the rocker arm pivots and thus the rocker cannot be stabilized by mounting it on a shaft. Rather, the rocker arm must be, and is, maintained in its proper position by cooperation between a convex, hemi-spherical feature of the hydraulic lash adjuster and a complementary concave, hemi-spherical feature on the rocker arm.
This mounting arrangement has not always proven to be satisfactory as side loads on the assembly may result in movement of the rocker arm out of its desired, operating position. Additionally, there are limits to the extent of rocker arm rotation and valve lift which, if exceeded, will again result in movement of the rocker arm out of position. The present invention addresses this problem.
Because the hydraulic lash adjuster, the rocker arm and the valve stem are aligned in a vertical plane and the lash adjuster and valve stem often define converging axes, it is quite common that features of the cast cylinder head designed to mount the lash adjuster and provide suitable wall thickness will result in a protrusion or boss in the intake or exhaust port which increases flow resistance and thus reduces intake and exhaust flow. This is obviously undesirable and the present invention also addresses this problem.